1) Field of the invention
The present invention relates to a microscope used for a virtual-slide creating system.
2) Description of the Related Art
Conventionally, in specimen observation by a specialist in pathology using an optical microscope, there has been adopted a technique that includes shifting of a stage (or a specimen on the stage) for searching a site to be examined while observing the entire image of the specimen using a low-magnification objective about 10× or 20× and subsequent enlargement and close observation of the very site upon changing to a high-magnification objective about 40×.
However, moving the stage (or the specimen on the stage) and changing the objective for changing the field and enlarging the image each time of observation of the site to be examined complicates the operation. In addition, in a case where a plurality of sites to be examined are scattered over a specimen, it is difficult to grasp a relative position of each site in reference to the entire region of the specimen, and thus a great effort is required for identifying pathological changes.
In this case, if a specialist in pathology tries, using an optical microscope, to divide the specimen into a plurality of minute segments, to capture an enlarged image for each segment and to patch these images together for the purpose of grasping a relative position of each site in reference to the entire region of the specimen, it involves such enormous trouble and time as to prevent the specialist from making volumes of diagnosis and thus possibly has unfavorable consequences to patients who wait for diagnostic result.
In addition, under the recent circumstances where shortage of medical specialists is recognized as a problem, most of small- or middle-scale hospitals and remote-area facilities are without specialists in pathology. Furthermore, there are special and rare pathological changes that are difficult to diagnose for others than specialists in pathology of special fields. In such a case, a specimen on a slide glass has to be transported to ask for diagnosis by such a specialist in pathology of the special field, and thus it takes substantial number of days until the diagnostic result is available.
In recent years, proposals have been made for a virtual-slide creating system, which makes it possible to make simulative microscopic observation by, upon preliminarily capturing and accumulating a specimen on a slide glass as high-definition digital images, displaying the digital images of the specimen on a display unit of a personal computer or the like as controlling magnification and observation position.
A virtual-slide creating system is generally configured to have: a microscope provided with an illumination optical system, an image capture unit, and a stage which holds a specimen is movable in predetermined directions; a control means which conducts overall control of the system including operation control of the components thereof; and a storage means which stores digital images captured by the image capture unit. The control means segments the observation region of the specimen on a slide glass into microregions in accordance with a magnification, makes the image capture unit sequentially scan the microregions to capture images while moving the stage, and makes the storage means store the images upon adding positional data of the individual microregions in reference to the entire image corresponding to the entire observation region. In addition, for each microregion, images focused on respective depths, which are predetermined for each specimen, are captured. In this way, the virtual-slide creating system is designed to capture and store, for each predetermined magnification, images of three-dimensional regions regarding the specimen.
The digital image data created by the virtual-slide creating system can be utilized so that an image of a desired observation site with a desired magnification is displayed on a display screen of a network-connected computer of a specialist in pathology via a virtual-slide display system.
Therefore, use of the virtual-slide system can dispense with complicated operations as required for pathological diagnosis using a conventional optical microscope, lighten a work required for identification of pathological changes, and save time. In addition, since a virtual slide is composed of digital data, digital image data of a specimen can be transmitted to a specialist in pathology in no time even from a remote area, so that an early diagnostic result can be obtained from the specialist.
In addition, digital data of a specimen is sharable. Therefore, it is possible to ask for observation and diagnosis on the same specimen at the same time by a plurality of specialists in pathology. Also, use of virtual slides as a teaching material for medical students can save the trouble of individually preparing specimens on slide glasses as well as assure the equal quality of teaching materials.
Further, use of a virtual slide makes it possible to illustrate the diagnostic result in front of the patient showing images of the specimen on a display unit.
Conventionally, there are some examples of a microscope used for virtual-slide creating system where the observation optical system is configured to include a dry objective of 20× and a dry objective of 40× which are exchangeable to one another, and when the priority is given to the scanning speed, the dry objective of 20× is used, while when the priority is given to the image definition, the dry objective of 40× is used. This type of microscope for virtual-slide creating system where dry objectives are exchangeable is recited in U.S. Pat. Nos. 6,101,265 and 6,272,235, for example.
Alternatively, there are some examples of a microscope used for virtual slide creating system where the observation optical system is configured to include a dry objective of 20× and a magnification varying lens of 2×, and when the priority is given to the scanning speed, only the dry objective of 20× is used, while when the definition by the image capture unit is unsatisfactory, the objective is combined with the magnification varying lens of 2×, to achieve the total magnification of 40×. This type of microscope for virtual-slide creating system where an objective combined with a magnification varying lens is disclosed in “ScanScope XT System” by Aperio (a web page found via search on Oct. 1, 2008, http://www.aperio.com/PDF_docs/quicklinks/XT%20Data.pdf).